From the National Institute on Deafness and Other Communication Disorders
From the National Institute on Deafness and Other Communication DisordersAphasia is a condition caused by damage to parts of the brain responsible for language. In most people, these areas are located on the left side (hemisphere) of the brain. Aphasia develops suddenly, often as a result of a stroke or head injury, but can also develop slowly, such as with a brain tumor, an infection or dementia. The disorder impairs the expression and understanding of language, as well as reading and writing. Aphasia can occur in combination with speech disorders such as dysarthria or apraxia of speech, which are also caused by brain damage.
Who has aphasia?
Anyone can develop aphasia, including children, but most people with aphasia are middle-aged or older. Men and women are affected equally. According to the National Aphasia Association, approximately 80,000 people develop aphasia each year as a result of a stroke. Approximately one million people in the United States currently suffer from aphasia.
What causes aphasia?
Aphasia is caused by damage to one or more language areas in the brain. Often the cause of brain damage is a stroke. A stroke occurs when blood cannot reach part of the brain. Brain cells die when they do not receive the normal blood supply, which carries oxygen and important nutrients. Other causes of brain damage include severe blows to the head, brain tumors, brain infections, and other conditions that affect the brain.
What types of aphasia are there?
There are two broad categories of aphasia: fluent and non-fluent. Damage to the temporal lobe (side) of the brain can result in a fluent aphasia, called Wernicke's aphasia (see figure). In most people, the damage occurs in the left temporal lobe, although it can also be caused by damage to the right lobe. People with Wernicke's aphasia may speak in long sentences that have no meaning, add unnecessary words, and even make up words. For example, someone with Wernicke's aphasia might say, "You know that smoodle has turned pink and I want him close by and care for him the way you wanted before." As a result, it is often difficult to follow what the person is trying to say. People with Wernicke's aphasia typically have great difficulty understanding speech and are often unaware of their errors. These individuals usually do not have physical weakness because their brain damage is not located near the parts of the brain that control movement.
One type of disfluent aphasia is Broca's aphasia. People with Broca's aphasia have damage to the frontal lobe of the brain. They often speak in short sentences that are logical, but produced with great difficulty. They often leave out small words like 'is', 'and' and 'the'. For example, a person with Broca's aphasia might say, "Walk the dog," which means, "I want to take the dog for a walk," or "book book two table," for "There are two books on the table." "People with Broca's aphasia usually understand the speech of others quite well. As a result, they are often aware of their difficulties and become easily frustrated. People with Broca's aphasia often have right-sided weakness or paralysis of the arm and leg, because the frontal lobe is also important for motor movements.
Another type of non-fluent aphasia, global aphasia, results from damage to large parts of the language areas of the brain. People with global aphasia have severe communication problems and may be very limited in their ability to speak or understand language.
There are other types of aphasia, each caused by damage to different language areas of the brain. Some people may have difficulty repeating words and phrases, even though they can speak and understand the meaning of the word or phrase. Others may have difficulty naming objects, even though they know what the object is and what it can be used for.
How is aphasia diagnosed?
Aphasia is usually first recognized by the doctor treating the person for his or her brain injury. This is often a neurologist. The doctor typically performs tests that require the person to follow commands, answer questions, name objects, and have a conversation. If the doctor suspects aphasia, the patient is often referred to a speech therapist, who will conduct a comprehensive assessment of the person's communication skills. The examination includes the person's ability to speak, express ideas, converse socially, understand language, read and write, as well as the ability to swallow and use alternative and augmentative communication.
Where can I get more information?
The NIDCD maintains a directory of organizations that can answer questions and provide printed or electronic information about aphasia. See the list of organizations atwww.nidcd.nih.gov/directory.
National Institute on Deafness and Other Communication Disorders
National Institutes of Health
31 Mid-drive, MSC 2320
Bethesda, MD, VS 20892-2320
E-mail:nidcdinfo@nidcd.nih.gov
